1. Field of the Invention
The present invention relates to a pump-actuated sequencing valve and system for sequentially administering, to a patient, two fluids contained in separate respective reservoirs, the fluid being pumped from one of the two reservoirs by means of a pump associated therewith.
2. Description of Prior Art
In the medical treatment of patients, it is frequently required to sequentially administer, to a patient, two different fluids. For example, in the area of digital fluoroscopy, sequential administration of a contrast media and a saline solution is required.
One technique of the prior art called for the contrast media to be poured into a cylindrical reservoir, followed by careful pouring of the saline solution into the reservoir on top of the contrast media. Since the contrast media is a more dense substance than the saline solution, it was hoped that the contrast media would remain, in an unmixed state, in the bottom portion of the cylinder, such that, when pump pressure was applied from the top of the cylinder, the contrast media would be forced into the intravenous feedline ahead of the saline solution.
The problem with this technique of the prior art was that even the most skilled and experienced person found it difficult to pour the contrast media and saline solution into the cylinder with such care as to prevent any mixing whatsoever of the two solutions. In addition, during the pumping procedure, mixing often occurred. Such mixture of the contrast media and saline solution has obvious harmful effects in terms of obtaining the best possible results from digital fluoroscopy procedures.
Medical administration sets for the dispensation of plural medical liquids from separate reservoirs have been developed. For example, see U.S. Pat. No. 3,886,937--Bobo et al and U.S. Pat. No. 4,324,238--Genese et al. However, these two cited patents are not suitable for the type of sequential administration involving the pumping of a contrast media via an intravenous feedline into a patient, followed by flow of other intravenous solution, such as saline solution, into the patient.
In addition, such arrangements of the prior art often do not preclude the backflow of solution from one reservoir into the feedline connected to the other reservoir.
Other patents generally pertinent to the invention disclosed herein are the following: U.S. Pat. No. 2,699,124--Moe; U.S. Pat. No. 4,103,686--LeFevre; and U.S. Pat. No. 4,215,695--Spitz et al.